And I'm Audie Cornish. A vaunted Capitol Hill dealmaker has died. Howard Baker was 88. He served as Senate Majority Leader and White House Chief of Staff, and he helped negotiate deals on everything from the Panama Canal Treaty to civil rights legislation and environmental laws. But Baker may be best-remembered for his role as Vice Chairman of the Senate Watergate Committee and for a certain key question he put to witnesses about misconduct by the Nixon administration. NPR's Brian Naylor reports.

BRIAN NAYLOR, BYLINE: This is the question that Howard Baker asked repeatedly in the Watergate hearings in the summer of 1973.

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HOWARD BAKER: One thing that keeps recurring to me and the one thing I've been trying to put to every witness that has unique information, in addition to their own personal information - just what did the president know, and when did he first know it?

NAYLOR: What did the president know, and when did he know it, became something of a catchphrase in American politics. Baker told an interviewer recently it just came to him one day that Summer.

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BAKER: I was at lunch in the Senate office building, and I mused out loud, these hearings aren't going anywhere. They have no purpose - no focus. What we really need to know is, what did Richard Nixon know? And more important still, when did he know it?

NAYLOR: Baker was seen as a Nixon ally when he was named the ranking Republican on the Senate panel that investigated the Watergate break-in. But he later told the AP that, quote, "after a few weeks it began to dawn on me that there was more to it than I thought and more to it that I liked." Howard Baker was born to politics. His father was a congressman from Tennessee, and when his father died Baker's stepmother succeeded him. Baker lost his first try for elective office in 1964, but two years later he ran again and became the first Republican popularly elected to the Senate from Tennessee. In 1980, Baker made his own try for the White House, but dropped out after finishing third in the New Hampshire primary. He left the Senate after the 1984 elections, joining a Washington law firm, but in 1987 he was tapped by President Reagan to become White House Chief of Staff. It was in the midst of another scandal - what was called the Iran-Contra scandal, in which administration officials sought to sell arms to Iran and use the proceeds to fund the U.S.-backed antigovernment rebels in Nicaragua. Baker was credited with getting the White House back on an even keel. In his Senate career, Baker was seen as a dealmaker. He helped win passage of The Panama Canal Treaty and supported civil rights and environmental legislation, including creation of the Big South Fork National River and Recreation Area in his home state.

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BAKER: My greatest accomplishment, I'm sure, was the body of environmental laws passed because I had a profound influence on the future of the country. It had an impact on the people of this region and the rest of the country.

NAYLOR: Republican Senator Lamar Alexander of Tennessee said Baker was a mentor. His favorite story was when Baker delivered his first speech on the Senate floor and asked the then-Republican leader Everett Dirksen, who also happened to be his father-in-law, for a review.

SENATOR LAMAR ALEXANDER: Senator Baker spoke a little long. And Senator Dirksen walked over, and his son-in-law said, well, Senator Dirksen, how'd I do? And Senator Dirksen said to Howard, Howard, maybe occasionally you should enjoy the luxury of an unexpressed thought.

NAYLOR: Alexander says no one outside his family had more influence on him than Baker, who he says had the kind of political skills that are now in short supply. Brian Naylor, NPR News, Washington. Transcript provided by NPR, Copyright NPR.